Gold nanoparticles have many advantages over the organic dye molecules now used to study cells with fluorescence microscopy. They are less toxic to cells, more sensitive, probe over a longer distance, and are more photostable – meaning they are unchanged by light exposure.

University of Strathclyde scientists took these advantages into account when developing a multidisciplinary approach to image messenger RNA (mRNA) – a kind of nucleic acid present in all living cells that carries genetic codes from DNA to make protein. By examining key mRNAs at a cellular level, the scientists could be able to detect diseases such as cancer at an early stage, and study the effectiveness of treatments.

“The nanoprobes are based on a type of ‘molecular handshake’ called [FRET], in which gold nanoparticles are linked with a fluorescent protein via a hairpin-structured single-stranded DNA,” said Dr. Yu Chen of the university’s department of physics. “Upon interacting with the target mRNA in the cell, the hairpin structure dissolves, and a fluorescent signal occurs – enabling the tracking and quantification of the disease-related mRNA at a cellular level, even down to the level of single molecules.

“The technology could allow the simultaneous detection of multiple types of RNA related to cancer, which would then raise the possibility of scientists eventually being able to screen patients in order to predict their risk of developing disease,” Chen said. “By allowing us to see what is happening inside cells, we also hope this research will lead to the development of techniques to study the efficacy of drugs.”

The gold probes could also deliver cancer drugs and other molecules directly to disease tissues, bypassing healthy cells, and the researchers also believe the technique could improve food and water safety.

“This new approach to imaging RNA at a single-cell level may also allow scientists to develop new methods to identify various microbes which may have contaminated food and water,” said Dr. Jun Yu of the Strathclyde Institute of Pharmacy and Biomedical Sciences. “Food safety is a global challenge, and using novel nanoprobes to detect food contamination by various microbes will open up a new way of addressing this crucial issue.”

The 18-month project was backed with a £119,000 investment from the Biotechnology and Biological Sciences Research Council.